Rod mill



April 25, 1933. I c. H. MACDONALD 0 7 Filed April 4, 1930 s Sheets-Sheet 1 ATORE April 25, 1933. c. H. MACDONALD ROD MILL 3 Sheets-Sheet 2 Filed April 4, 1930 I l/l/l/II/ I ll/ III/III If I NVENTOR BYEhuflEs HMUJ: mid.

ATTORNEY April 25 1933 c. H. MACDONALD 1,905,417

ROD MILL Filed April 4, 1930 s she'e'ts-s eet 5 INVENTOR EP LELHEE HMmzdun d- ATTORNEY This invention relates to improvements inv Patented Apr. 25, 1933 PATENT OFFICE CHARLES H. MACDONALD, OF SAN FRANCISCO, CALIFORNIA.

non MILL Application filed April 4, 1930. Serial No. 441,511.

rod mills and more particularly to mills for reducing pulp and fibrous products.

Among the objects of the invention are to simplify the structure and-increase the efliciency of this class of mills.

Another object is to improve the feed and distribution of products passing into and through the mill.

Another object is to insure the positive and uniform operation of the crushing rods.

A further object is to reduce the interstitial displacement of the rods.

Other objects and advantages will appear as the description progresses.

In this specification and the accompanying drawings the invention is disclosed in its pre ferred form. But it is to be understood that it is not limited -to this form because it may be embodied in other forms. It is also to be understood that in and by the claims following the description it is desired to secure this invention in whatsoever form it may be embodied. F 1 a In the three sheets of drawings Fig. 1 is a plan View from above of a rod mill constructed and arranged in accordance with this invention.

Fig. 2 is an enlarged detail in vertical cross section of the same, taken on the line IIII.

Fig. 3 is a longitudinal vertical section of the same, taken on the line IIIIII.

Fig. 4 is a diagrammatic end elevation par tially in vertical section, showing a modified application of the rod mill submerged in a vertical tank having a screening and circulating system. v

In detail the construction illustrated in the drawings, referring to Fig. 1, comprises an enclosing casing or tub I, having the longitudinal partition 2, extending upward from the bottom 3 thereof.

The segmental apron 4, extends transverse- I 1y between the partition 2 and the adjacent side wall 5, and upward from the bottom 3. From the apex 6 the apron slopes down to the bottom 3 again. This arrangement creates a substantially circular path for the flow of pulp when propelled by the rod mill.

The rod' mill comprises the flanged cylindrical drum 7, with the heads 8 and 9 bolted to the flanges at 1010. The head 8 is a flatdisc fixed to the end of the shaft 11. The opposite head has the hollow trunnion 12, closed by the flanged cap 13 bolted thereto. The end 14 of this cap is flush with the innerplane of the head 9.

The shaft 11 and trunnion'12 are j ournaled in suitable hearings in the pillow blocks 14 and 15 on the floor on opposite sides of the tub 1. The drum is driven in any suitable manner and revolves between the partition 2 and the wall 5, adjacent theapron 4, the curve of which is concentric with the periphery ofthe drum. 66

The drum has the series of interspaced openings 16 separated longitudinally by the bars 17--17 and circumferentially .by the bands 18 18, making'in effect a peripheral integral grid work surrounding the openings 16. For greater rigidity the bands 18-18 are channel or T shape in cross section.

The lugs 1919 are cast integrally with the bands 18-18. The fly bars 2020 are secured between these lugs 1919 by the bolts 21. The ends of the fly bars rest within notches formed in the flanges 10 and the heads 8-9.

The interior of the drum is provided with the annular rows of elevators 22-22 consisting of a series of humps or corrugations which have a biarcuate contour. These are preferably formed in segments containing three or more humps, depending upon the diameter of the drum. These segments are preferably alined with the bands 18-18 through which they are bolted by the bolts 23, the heads of which are countersunk into the segments, with the nuts bearing against the outside of the bands 18.

These elevators are arranged in longitudinal alinement with the openings 16 so that the rods 24 cannot obstruct free passage of pulp through the openings 16. v

The rods 24-25 lie within the drum parallel with the axis of the shaft 11, from end to end of the drum, with a slight end play. The heads 8914 have the liners 26 fixed thereto to take thewear incidental to the end thrusts of the rods. The rods 25 are smaller in diameter for greater interstitial efliciency, the smaller rods reducing the interstices 27 existing between the larger rods 24. The rods are introduced into and removed fromthe drum through the hollow trunnion 12, closed by the cap 13.

The present embodiment of this invention adapts it particularly to the grinding,squeezing and maceration of Wood pulp and the like. The pulp in liquid suspension is introduced into the tub 1, up to the desired level. This submerges the lower portion of the drum.

Referring to Fi 2, the drum is revolved contraclockwise. he semi-fluid pulp is elevated by the fly bars 20 cooperating with the tom of the tank. The bottom of the sump is formed by the plate 32 bolted to the tank 29.

The discharge nipple 33 is screwed into this plate and has the draw-01f valve 34 for withdrawing the milled pulp.

The screen 35 rests upon the plate 32 and is curved concentrically with the bottom of the tank. The fly bars in this instance may be strips of hard wood so as not to wear the screen 35 should they contact it. They constantly sweep the surface of the screen to keep its meshes open when pulp is being drawn off from the sump beneath.

After the initial breaking up of the pulp in the tank 29, the valve 36 may be opened to the pump 37, which sucks the pulp 31 apron 4 and descends through the holes 16 through the pipe 38 and, discharges through into the drum among the rods 2425. In the initial stages the pulp may be coarse and heavy and filled withslabs and chunks of lap or compressed pulp. These striking the baffle bar 27 fixed to the cover 28, across the width of the drum, aids in forcing the pul into the drum through its periphery.

'I he rotation of the drum causes therods to tumble downward from the internal periphery of the drum, whence they are raised by the elevator humps 22. The rounding off of the humps 22, as shown, minimizes the wear on therods 24--25. These tumbling rods roll upon each other,crush, squeeze, and grindthe pulp therebetween finer and finer as the Operation continues, until the desired reduction is attained.

The pulp in excessof the capacity of the holes 16 is pushed upthe apron 4 and over the apex 6. This sets up a-circulation of the pulp on the opposite side of the partition 2 and back through the mill until the grinding of the batch of pulp is finished.

The initial grinding is facilitated by the addition of the shear bars 28 fixed'across the lower portion of the apron 4. These cooperate with the fly bars to shear and tear up the la s or chunks of pulp.

he general characteristics of the mill shown and described are equally advantageous for dry grinding, by modifications in the means for feeding and discharging the product into and from the mill. The inlet and outlet from the mill are through the periphery of the drum, as distinguished from mills fed and discharged axially through hollow shafts.

The modification shown in Fig. 4 comprises the mill of the eneral construction above described in detai located in the bottom of the tank 29.

This tank may be of any conventional construction, havin the semi-cylindrical bottom 30, conforming to the periphery of the 'mill, and in approximate contact with the fly,

bars 20.

The bottom of the tank has the sump 31 extending the length of the mill across the botthe pipe 39 back into the top of the tank 29.

The bypass 40 at a lower level on the tank has a valve 41 which may be opened to short circuit the discharge from the pump 37 after the coarse pulp has been broken up.

The vertical tank arrangement in Fig. 4 is desirable where floor space is a consideration, but the mode of operation is similar to that shown in Figs. 1, 2.

Having thus described this invention, what I claim and desire to secure by Letters Patent 1s:

1. A rod mill comprising a casing; a rotary drum having peripheral openings therein and mounted within said casing; a segmental apron in said casing adjacent the periphery of said drum; radially disposed fly bars on said periphery between said openings and c0- operating with said apron and rods within periphery adjacent said openumps on the interior of said openings in its periphery; -fly bars on said periphery adjacent said openings and cooperating with said apron; and a plurality of rods within said drum.

In testimony whereof I have hereunto set my hand this 27th day of March, 1930.

CHARLES H. MACDONALD. 

